1. Field of the Invention
This invention relates to a subterranean well tool for anchoring a tubing string within a well conduit and for providing a fluid passage for the injection of well treatment fluids through a flow line to a subsurface position below the well tool.
2. Description of the Prior Art
It is often necessary to inject fluids from the surface of a subterranean oil or gas well to a subsurface location. For example, it may be necessary to inject well treating fluids at a subsurface production zone. In many wells, the produced fluids are highly corrosive and it is often necessary to inject corrosion inhibitor to prevent damage to the production tubing string and to well completion tools. In many applications, it is necessary to inject treating fluids of this type while the well is producing. Conventional applications have employed dual tubing strings in which a smaller diameter tubing string is used to inject fluids while production continues through a larger bore tubing string. Conventional dual string well tools in which the two tubing strings can be attached through separate bores have been developed in part for such applications.
In addition to the conventional dual tubing string completions, other well completions have employed a single production tubing string with a smaller diameter continuous flow line comprising continuous tubings conventionally available in lengths of 300-1000 feet attached to the exterior of the individual tubing joint sections comprising a conventional production tubing string. Such injection flow lines generally have an outer diameter of approximately 1/4 inch and can comprise tubing commonly referred to as control line tubing used for hydraulic pressure control in subsurface well tools.
When the use of external continuous injection tubing attached to production tubing joints, conventionally having a length of 30 feet, the interference with the flow of produced fluids through the production tubing string by the injection apparatus should be minimal. Such injection line completions can, however, interfere with the apparatus necessary for conventional produciton techniques. For example, it would be highly undesirable for the injection apparatus to reduce the production efficiency of conventional techniques, such as sucker rod pumping. Conventional sucker rod pumps are used to lift produced fluids from a subsurface zone having an insufficient bottom hole pressure to independently sustain production to the well surface. Conventionally, a sucker pump is seated on a pump seat located at the bottom of the production tubing string. A sucker rod string extending through the production tubing to the surface of the well is used to manipulate the pump. It is highly desirable that the production tubing be anchored to the casing of the well bore during sucker rod pumping operations to prevent vertical movement of the tubing during the pump cycle.
Conventional tubing anchors or anchor-catchers, such as that disclosed in U.S. Pat. No. 3,077,933, which is commercially available as shown on pages 1036-1039 of the "1982-83 Composite Catalog of Oil Field Equipment and Services", published by World Oil, can be used to prevent tubing overstress and prevent excessive rod and tubing wear. Frictional rod drag can also be prevented by the use of a tubing anchor, thus reducing surface power requirements. The conventional tubing anchor catcher apparatus shown in U.S. Pat. No. 3,077,933 employs radially expandable anchoring slips which are actuated by rotation of the tubing string. Such rotationally set well tools are highly desirable when used to prevent excessive axial movement of the tubing string. Conventional rotationally set anchor catchers cannot, however, be used with external injection flow lines attached to the tubing. An externally attached flow line, rotating with the tubing, would interfere with expansion of the anchoring slips during rotation of the tubing string to which the injection tubing is attached.